1. Field of the Invention
The invention relates to a snow making apparatus comprising at least one water/air nozzel which is adapted to eject a water/air mixture. The invention further relates to a method of operating a snow making apparatus.
2. Description of the Related Art
Snow making apparatuses (so-called “snow cannons”) of various configurations are used in winter sports areas. DE 196 27 586 A1 gives an overview of known types of construction of snow making apparatuses. These include, in particular, high-pressure cannons close to the ground, high-pressure cannons of a lance type of construction (tower construction) and low-pressure cannons with a propeller.
High-pressure cannons close to the ground use compressed air to produce a water/air mist which is expelled at high speed in order to achieve the desired throwing range and active cooling due to rapid air expansion. Considerable quantities of compressed air are required. A central compressor is generally provided for a plurality of cannons, the compressor having a power rating of, for example, 15 to 20 kW.
With high-pressure cannons of lance form, the water/air nozzles are arranged at a height of 8 to 12 m above the piste. Lower expulsion rates may be employed, owing to the prolonged falling path. Therefore, the air compressor may have only, for a high-pressure cannon, a relatively low power rating of, for example, 5 kW per lance. A cannon of this design is shown in DE 196 27 586 A1.
With low-pressure cannons, a propeller produces a main air stream into which freezing nuclei are sprayed by means of nucleator nozzles and small water droplets are spayed by means of water nozzles. The nucleator nozzles are constructed as water/air nozzles. They are operated with compressed air and water under pressure and atomise a water/air mixture. The compressed air relaxes as it issues from the nucleator nozzles and thus cools water droplets of the water/air mixture to well below the freezing point so that small ice crystals are formed. The droplets discharged by the water nozzles settle on these freezing nuclei and thus form the snow crystal. With cannons of this design, compressed air which typically, as with the other designs mentioned, has to have a pressure of approximately 4 to 10 bar is required only for the nucleator nozzles. A compressed air power rating of about 4 to 5.5 kW is typically required. DE 41 31 857 A1 shows one such snow cannon with a screw compressor flanged on to the main motor.
With all the designs described hitherto, the snow making apparatus requires compressed air which has to be provided by a local or central compressor. This causes additional, considerable energy consumption. The compressor increases the production costs, requires maintenance and causes noise. In addition, proper working is not always ensured, in particular, at low temperatures. A compressor mounted on the snow making apparatus increases the weight thereof by about 120 kg, whereas a central compressor necessitates the laying of compressed air lines.
DE 44 23 124 A1 discloses a snow making apparatus of a propeller type of construction, which does not require an additional source of compressed air. The freezing nuclei are formed here by an auxiliary nozzle which is arranged in the main air stream. With this apparatus, which is dependent on the propeller type of construction, a propeller drive has to be provided that is dimensioned correspondingly more powerful.